If Sharapova’s legions of fans felt trepidation before her opener against Dulko, they should have left that match reassured not just about her ankle but about the state of her game overall. Far more impressive than in her last two Melbourne appearances, the Russian moved more and more crisply as the match progressed while suffering only one brief serving lapse and returning serve with her familiar ferocity. Knowing the quality of her opponent, and remembering her loss to her at Wimbledon 2009, Sharapova may have benefited from a match that forced her to focus immediately. A draw that initially seemed unkind now grows more benign with a clash against an American qualifier. Or does it? The Siberian siren has recorded mixed results against American youngsters before, falling to Oudin in a US Open epic and double-bageling Beatrice Capra a year later. As she admitted, Sharapova knows virtually nothing about Jamie Hampton’s style and may need a few games to adjust to it. At the same time, though, Hampton almost certainly never has played an opponent who can generate power approaching the Russian’s baseline bombardment.

More in doubt are several other matches on Day 4, to which we now turn our attention.

Hewitt vs. Roddick: Although the head-to-head between these two grizzled veterans stands at 7-6 in Roddick’s favor, the American has won their last six meetings in a span stretching back to 2005. But Hewitt continues to threaten his far more powerful rival with his agile movement, clever point construction, and unrelenting patience. Three of their last four meetings reached final sets, including a Wimbledon thriller, while the fourth featured two tiebreaks. Relying upon the support of the Rod Laver crowd, Hewitt may fancy his chances of swinging those few crucial points in his direction this time. The stark disparity between their serves should play a less significant role than on the grass and fast hard courts where Roddick won all six matches in his current streak. All the same, the American advanced impressively past a talented opponent in Robin Haase, showing more purpose and poise than usual, whereas Hewitt struggled to deliver the coup de grace against an anonymous obstacle. Through most of the tennis world, Roddick will go into history as the more accomplished player, but one should note that Hewitt almost certainly will retire with more major titles, including the Wimbledon crown that the American so desperately covets.

Zvonareva vs. Hradecka: Extended for more than three hours by Alexandra Dulgheru, Zvonareva may arrive in the second round physically and mentally jaded by a match that hung in the balance for an excruciating length. The Russian typically has struggled with heavy servers (see S for Stosur), so Hradecka’s penetrating delivery may cause her anxiety if supplemented by the groundstroke missiles that she showcased in Auckland during a victory over Peng. Can she finish what Dulgheru started? The speed of these courts tilts towards Zvonareva’s advantage, however, showcasing her balanced game more effectively than the raw firepower of her still-evolving opponent.

Bellucci vs. Monfils: One might understate the situation to say that Monfils has produced drastically different results from one major to the next. After his comeback five-set victory over dirt devil at Roland Garros, many fans exulted that Monfils finally had found the purpose that he long had lacked. Then came an unexpected Wimbledon loss to Lukasz Kubot and a thoroughly disappointing US Open setback against Ferrero. After those setbacks, a strong Australian Open would seem likely for a player whose career has constituted a sequence of peaks and valleys. Further suggesting that possibility was a strong week in Doha, highlighted by a semifinal victory over Nadal. Full of talent and ambition, meanwhile, Bellucci has struggled to harness his lefty power at crucial moments in matches. Before he ended last season with seven straight losses at ATP tournaments, the top-ranked Brazilian defeated Murray and Berdych consecutively at the prestigious event in Madrid. This enigma could trouble Monfils by curving his lefty forehand into the Frenchman’s modest backhand and by winning the battle of court positioning. But Bellucci has developed little of the tactical sense necessary to topple an opponent superior in athleticism, fitness, experience, and nearly all other meaningful areas.

Raonic vs. Petzschner: Not known for their returning talents, both of these huge servers broke their opponents repeatedly during emphatic first-round victories. In fact, Petzschner fell just two games short of the first triple-bagel at the Australian Open since the 1970s and first at any major since 1993. While his opponent’s ineptitude likely played a role in that development, the German has ridden waves of confidence to impressive accomplishments before. Contesting a five-setter with Nadal two Wimbledons ago, he shares Raonic’s preference for faster surfaces. The high bounce of this court should aid the Canadian’s monstrous kick serve, one of the reasons why he reached the second week here last year. With his hip injury now behind him, Raonic must win matches like these to deliver a statement to his peers about his renewed progress.

Golubev vs. Gasquet: Slugging his path past the more talented Youzhny in the first round, Golubev confronts a very similar task in the artful Gasquet. Like the Russian, the Frenchman unleashes stylish one-handed backhands but lacks the muscular force projected by the Kazakh, who has rebounded impressively from an 18-match losing streak in 2011. When a match turns for or against either of these players, it generally swings dramatically. In the best-of-five format, neither probably can sustain their high-risk tactics for long enough to win without a lull, which will give the opponent a chance to reassert himself. One senses that a match of momentum shifts might evolve as Golubev’s unvarnished ball-bruising pounds away at Gasquet’s psyche in addition to his defenses. If he can stay positive, though, the Frenchman should withstand many of those first strikes and outlast the assault.

Stephens vs. Kuznetsova: Succumbing twice to Christina McHale in 2011, the two-time major champion now faces another opportunistic American teenager. Stephens enjoyed her emergence during last summer, when she reached a San Diego quarterfinal and the third round at the US Open with an upset over Peer. Seeking to duplicate that feat in Australia, she meets a player who already has alternated the encouraging (Auckland semifinal performance, Sydney victory over Zvonareva) with the discouraging (a first career loss to Zheng and a retirement against Safarova). Illustrating the rollercoaster that Kuznetsova regularly rides was her three-set victory over Scheepers, which started with a comfortable set, continued with a desultory second set, and ended abruptly with a third-set bagel. Although she can deliver slightly more offense than her fellow rising Americans, Stephens remains a counterpuncher against whom the Russian will need to hit her targets consistently. Anyone who has watched Kuznetsova could tell you that she finds this task less easy than she should.

Simon vs. Benneteau: When these two compatriots collide, their promising performances at preparatory tournaments should provide them with plenty of momentum. A semifinalist at Brisbane, Simon will duel with the Sydney runner-up in a match between a player who clings to the baseline and another who ventures into the forecourt more boldly than many. As Benneteau tries to shorten points, his countryman will try to extend them with the same tenacity that carried him to a quarterfinal in Melbourne two years ago. While he has faded since his breakthrough in 2008-09, Simon remains within range of the top 10 and certainly has maximized his potential. In the Melbourne heat, this counterpuncher’s grinding style should prove especially lethal.

Llodra vs. Bogomolov, Jr.: Unheralded until last year, the Russian-turned-American-turned-Russian seems to have weathered the controversy over his nationality with little concern. A win here would move into the third round, justifying his seed and accomplishing the difficult task of maintaining momentum during the offseason. By the standards of this journeyman, that accomplishment would deserve credit, especially following the early demise of more celebrated compatriots. Overcoming perhaps the ATP’s most maddening player in Gulbis, Llodra may find greater resistance from someone who generally competes more vigorously (except at the Paris Indoors). Aware that the Frenchman will attack the forecourt consistently, Bogomolov needs to refine his passing shots and aim to keep his opponent behind the baseline in rallies that expose his erratic groundstrokes.

Makarova vs. Kanepi: The flavor of the fortnight at the 2010 Australian Open, this lesser Russian built upon an upset of Ivanovic to reach the second week and challenge eventual champion Clijsters for a set when she arrived there. This year, she delivered two bagels in her opener as memories of Melbourne likely flooded back into her mind. An unseeded champion in Brisbane, Kanepi entered this tournament as perhaps its most compelling dark horse. With straight-sets victories over Pavlyuchenkova, Petkovic, and Schiavone during the first week of 2012, she showcased a more formidable serve than ever and rarely faced a break point throughout the tournament. Even more notable was Kanepi’s improved shot selection and consistency, areas that had retarded her progress until now. But the question lingers as to whether she enjoyed a career week in Brisbane or whether her accomplishment laid the foundation for something greater. After all, everyone knows what the Brisbane champion did last year.

And, of course, we could not complete a preview of Day 4 without…

Ivanovic vs. Krajicek: Never forced to face a break point throughout her opening victory, the former #1 dominated beyond her serve against an overmatched opponent and thus could afford to attack her returns aggressively. To be sure, the knowledge of Dominguez Lino’s weak serve may have enabled Ivanovic to relax and swing more freely during her own service games, but that shot has shown steady signs of improvement throughout her partnership with Nigel Sears. When she faces an opponent with a more imposing serve in Krajicek, Ana will face greater pressure to maintain her own delivery. This match likely will consist of short points punctuated by staccato winners or unforced errors. A former prodigy derailed by injuries, Krajicek impressed us with her ball-striking and her poise when we watched compete creditably against an aging Hingis in San Diego five years ago. Although injuries have derailed her since then, she remains a player more dangerous than her ranking would suggest. Handle not with complacency but with confidence and calm.